I was just looking around the net and found a game called Flightgear anyone ever played this? looks pretty cool for nothing

I remember seeing that on one of those "free games" adverts on MyFace, but they wanted me to install their software so I can download it. Looks rather amazing, if only I had my joystick with me

Seems like not a bad game tbh. Only thing is my pc has trouble playing it.

From what I understood it's not a game but an attempt at a freeware full blown flight simulation, which should really be a lot easier to achieve than a racing sim because an aircraft is a lot simpler to model.

I did try it once ages ago but couldn't find a way to remap the joystick so it was a waste of time but it may have moved on.

Quote from ajp71 :

From what I understood it's not a game but an attempt at a freeware full blown flight simulation, which should really be a lot easier to achieve than a racing sim because an aircraft is a lot simpler to model.

Ummmm... not? Aircraft have moving flight surfaces, and engines, and weather plays a much bigger role. There are also many more part failures to take into account, and things such as icing on the wings. X-Plane has a fairly sophisticated tire model for planes on the ground, as well as a "water model" for seaplanes. Whereas LFS only has to simulate downforce at a few spots, X-Plane models airflow over the entire surface of the aircraft, and lift points everywhere, including effects from propwash, turbulence, vortices, etc... One aiplane in X-Plane puts a much greater strain on the CPU than a car in LFS.

Quote from Stang70Fastback :

Ummmm... not?

Okay, how about this? An airplane is easier to get "roughly right" than a car physics wise. That's why you saw reasonably accurate flight simulators appear before you saw the same in racing simulators. Once you start going into that kind of detail though, none of them are easy problems.

Quote from Stang70Fastback :

Ummmm... not? Aircraft have moving flight surfaces, and engines, and weather plays a much bigger role. There are also many more part failures to take into account, and things such as icing on the wings. X-Plane has a fairly sophisticated tire model for planes on the ground, as well as a "water model" for seaplanes. Whereas LFS only has to simulate downforce at a few spots, X-Plane models airflow over the entire surface of the aircraft, and lift points everywhere, including effects from propwash, turbulence, vortices, etc... One aiplane in X-Plane puts a much greater strain on the CPU than a car in LFS.

The aerodynamics are the most complicated part of a flight model, they apply equally to a car but it gets far more important to take disturbed air flow into account due to proximity to the ground, other cars and more localised weather effects. The hardest part of car simulation is tire modeling which is still a bit of a dark art because no one really understands exactly how to work out how they work in the real world even with an infinite budget and expertise it's still partly trial and error and fudging. Car simulators really also struggle from the fact they're all rigid body simulations, this can be much more easily accounted for in a flight sim seeing as under normal loads the wings and only the wings aren't meant to flex in a predictable manner. I'm not saying that simulating aircraft is easy but to get a reasonably accurate model you do not need as much time and effort, whether you choose to go the fudging route (in which case it's really very simple) or whether you choose to go the dynamic route (in which case it's more a technical dilemma of getting real time CFD to work).

I also don't believe for a minute that X plane has an advanced tire model compared to any serious racing sim of the last decade...

Quote from ajp71 :

The aerodynamics are the most complicated part of a flight model, they apply equally to a car but it gets far more important to take disturbed air flow into account due to proximity to the ground, other cars and more localised weather effects. The hardest part of car simulation is tire modeling which is still a bit of a dark art because no one really understands exactly how to work out how they work in the real world even with an infinite budget and expertise it's still partly trial and error and fudging. Car simulators really also struggle from the fact they're all rigid body simulations, this can be much more easily accounted for in a flight sim seeing as under normal loads the wings and only the wings aren't meant to flex in a predictable manner. I'm not saying that simulating aircraft is easy but to get a reasonably accurate model you do not need as much time and effort, whether you choose to go the fudging route (in which case it's really very simple) or whether you choose to go the dynamic route (in which case it's more a technical dilemma of getting real time CFD to work).

I also don't believe for a minute that X plane has an advanced tire model compared to any serious racing sim of the last decade...

Unfortunately, X-Plane has just been upgraded to version 9 which means all the update history for version 8 has been taken off the site. I do remember then SPECIFICALLY stating that the tire physics would be good enough for a racing game.

As for air currents, disturbed air-flow close to the ground applies to aircraft too (ground effect.) And turbulence from other aircraft is also important when taking off behind other aircraft, flying in formations, or around varying terrain. All this is taken into account in X-Plane. And while there is the issue of tire physics which plays a much more important role in vehicle simulation, there are other factors in aircraft that do not apply to cars.

All I will say, is that the amount of things modeled in X-Plane at the moment truly dwarfs the Live for Speed vehicle model at this point.

Quote from Stang70Fastback :

I do remember then SPECIFICALLY stating that the tire physics would be good enough for a racing game.

I'd be amazed if it wasn't look up tables seeing as that's what most racing simulations are still using.

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As for air currents, disturbed air-flow close to the ground applies to aircraft too (ground effect.) And turbulence from other aircraft is also important when taking off behind other aircraft, flying in formations, or around varying terrain. All this is taken into account in X-Plane.

X Plane may take it into account or even simulate it but most flight sims get away with either completely ignoring it or botching it, only the terrain effects are necessary for all flight sims anyway and I doubt that many model the thermal properties of the runway that make an enormous difference to landing a light aircraft or likewise the sudden gusts or lack of wind that can easily put a poorly flown light aircraft into a very low stall.

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And while there is the issue of tire physics which plays a much more important role in vehicle simulation, there are other factors in aircraft that do not apply to cars.

What other factors are there that aren't vastly simpler to model?

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All I will say, is that the amount of things modeled in X-Plane at the moment truly dwarfs the Live for Speed vehicle model at this point.

But from what I can tell it's all very simple except for the aerodynamics which is mainly what X Planes about.

Quote from ajp71 :

...not a game but an attempt at a freeware full blown flight simulation

Open source, not freeware

Quote from Jarulf :

Open source, not freeware

An important difference, thanks for point that out I hadn't realised

I managed to contact Austin Meyer - the main developer behind X-Plane, and asked him the question we've been arguing about here, and pointed him to this forum. Here is his reply:

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It all depends on the detail to which you want to model things.

There is no doubt, at all, that when you look at the detail to which automotive simulators model the aerodynamics, their math will be the tiniest drop in the bucket compared to the OCEAN of data that is computed by x-plane

The aero physics of any car racing sim, compared to the aero physics in x-plane, are a grain of sand compared to a beach.

There is no doubt about that.

NOW, your question is: Which is harder to model.

MY answer is: To what degree of accuracy do you want to model?

To the degree of accuracy that x-plane models aerodynamics (full blade element theory) compared to the aero that is done for any PC racing sim (lift, drag, sideforce, downforce), there is simply no comparison.

If I were to ask the coders of the auto racing sims how they handle non-standard atmosphere, transonic drag rise, atmospheric changes with altitude from sea level to 400,000 feet, supersonic shock waves, moving parts and control surfaces, aerodynamic centers and damping, they would just sort look at me like i was crazy... they have never even CONSIDERED flying a porsche 911 at mach 2 at 100,000 feet with the difference in drag from the left side-view mirror being retracted, but not the right...

but x-plane does this.

It has to

It's a FLIGHT sim.

So, computing the physics of cars vs airplanes could be said to be identical... they are both moving bodies with possibly moving parts going through air.

BUT, when you look at how good a job people actually DO, there is no comparison between x-plane and automotive PC sims.

austin